@article{MAN_1975__215_162704,
     author = {A. Edward Nussbaum},
     title = {Extension of {Positive} {Definite} {Functions} and {Representation} of {Functions} in {Terms} of {Spherical} {Functions} in {Symmetrie} {Spaces} of {Noncompact} {Type} of {Rank} l.},
     journal = {Mathematische Annalen},
     pages = {97--116},
     publisher = {mathdoc},
     volume = {215},
     year = {1975},
     zbl = {0286.43011},
     url = {http://geodesic.mathdoc.fr/item/MAN_1975__215_162704/}
}